The Managing Director and Deputy CEO of Greece's Piraeus Bank has told CNBC its non-performing loans are still rising and that it will have to take further provisions for losses in the current quarter.

"The situation remains, to be honest, ugly. We still see month after month, quarter after quarter of new (NPL) formation," Anthimos Thomopoulos told CNBC.

"But the silver lining is that this process seems to be fading away. We are in the fourth quarter of declining rate of non-performing loan formation," he added.

Thomopoulos said NPLs – loans that are in or close to default - were rising at the rate of around 100 basis points per quarter, though this was an improvement from around 300 basis points three or four quarters ago.

As a result, Greece's second-largest lender expects to take further provisions in November. Thomopoulos said the provisions would be around 20 to 25 percent of its total loan book.

Piraeus bank reported loans in arrears over 90 days (NPLs) of 30 percent in its mid-year financial report released in August.

Thomopoulos denied that those NPLs were a result of a number of acquisitions the bank undertook earlier this year, when it bought the Greek deposits of the Bank of Cyprus, Cyprus Popular Bank and Hellenic Bank.

He said the assets the bank bought had already been "aggressively provisioned"

"We either bought good banks or we bought better books," he told CNBC.